Replaceable bit for drill rods



May 12, 1942. E. T. WISE ETAL 2,282,596

' REPLACEABLE BIT FOR DRILL RODS Filed Nov. 13, 1939 INVENTORS Edw-TWL s'e I BY Jos. .Z'. .GhzgZzez- Patented May 12, 1942 OFFlCE 2,282,596 REPLACEABLE BIT, FOR DRILL RODS Edward T. Wise and Joseph L. Ghigli'eri, Jackson, Calif.

This invention relates in general to an improvement in mining equipment, and in particular the invention is directed to an improved replaceable bit for drill rods.

The commonly used drill bit is formed integral with the drill rod, and when the bit becomes dull, the rod is taken out of service, and the bit resharpened; the resharpening being an expensive process, whether done slowly by hand, or speedily by automatic machines which are extremely costly.

The principal object of the invention is to provide a replaceable bit which is adapted to be used only once and when worn and dull, to be discarded and replaced with a new bit; this improved bit being simple and inexpensive to manufacture and therefore eliminates the time loss and expense of resharpening as at present.

Another object of the invention is to provide novel means for releasably securing the bit in non-rotatable relation on the drill rod; said means including an axially disposed bit securing screw arranged in unique manner so that the thrust and torque of the drill rod maintains the screw tight and properly seated at all times.

A further object of the invention is to produce a device which will be exceedingly efiective for the purpose for which it is designed.

These objects we accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of the folllowing specification and claim.

In the drawing similar characters of reference indicate corresponding parts in the several views:

Figure l is a side elevation of the device with the several parts in proper axial alinement but separated.

Figure 2 is a sectional elevation of the device with the several parts connected.

Referring now more particularly to the characters of reference on the drawing, the numeral I indicates a drill rod provided as usual with an axial water passage or bore 2 therethrough; the bit supporting end portion of the rod being increased somewhat in diameter, as at 3, to strengthen the same.

The drill bit, indicated generally at 4, is initially separate from the drill rod, and in general configuration is quite similar to the bit now commonly formed integral .on the drill rod; the working face of bit 4 including radially extending and axially projecting teeth 5 disposed in symmetrical and circumferentially spaced relation.

The bit is formed at its base or inner end with a plurality of radially extending lugs or tongues 6, preferably disposed in crossing planes, and projecting toward the adjacent end .of the drill rod portion 3, the lugs seating in corresponding grooves 1 formed in said adjacent end of portion 3. The outer edges of lugs 6 are chamfered as at 60,, while the cooperating inner edges of grooves I are beveled as at la whereby to prevent undesirable jamming or sticking of the lugs in the grooves and which might otherwise occur due to the heavy thrust or torque imparted from the drill rod to the bit through the lug and groove arrangement. When the lugs seat in the grooves, the remainder of the back end of the bit abuts'against the adjacent end of the portion 3 of the drill rod.

The bit is formed with an axial bore 8 which extends therethrough to receive a headed securing screw 9; the bore adjacent its outer end being enlarged in diameter as at 8a to receive the head ID of screw 9 in seated relation. The screw is formed with a left hand and preferably straight out thread II; the outer end of the water passage 2 in rod portion 3 being tapped out to receive such screw therein as clearly shown in Fig. 2. The screw is formed with an axial bore I2 which serves as a continuation of water passage 2 in the rod to feed water to the face of the bit as is necessary.

The bore I2 is non-circular in cross-section, and preferably square so that a tool may be projected into said bore to place or remove screw 9.

The inner circumferential edge of screw head I0 is chamfered as at l3, and this chamfer cooperates with a corresponding annular bevel I4 in the bottom .of the enlarged bore portion So; this assembly preventing the screw head from locking in the bore portion 8a.

The outer face of screw head It) is provided with projecting teeth Illa which are disposed symmetrical with teeth 5, but which terminate at their outer ends in the enlarged bore portion 811. some distance short of the outer ends of said teeth 5. The recessing of the screw head and its teeth as above assures that screw 9 does not at any time take the full thrust or torque of the drill rod, and yet the teeth Hm have sufficient bite to serve as an effective cutting medium for the central portion of a bore; the force imparted to the screw by engagement with the rock urging the screw in a direction to tighten the same and assures against loosening of the bit relative to the drill rod.

From the foregoing description it will be readily seen that we have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claim.

Having thus described our invention, what we claim as new and useful and desire to secure by Letters Patent is:

In a drill rod unit which includes a rod, an initially separate bit, and means detachably securing the bit axially on one end of the rod; said means comprising a screw having an enlarged circular head, the bit having an axial bore through which the screw projects from the bit face, the portion of the bore adjacent said face being enlarged to receive said head of the screw, said one end .of the rod being tapped to receive the screw; and a plurality of circumferentially spaced outwardly projecting radial teeth formed on the bit face about said enlarged portion of the bore and on the outer face of said screw head, the teeth on the bit face and screw head face being symmetrically formed and disposed.

EDWARD T. WISE. JOSEPH L. GHIGLIERI. 

